Throttle body with fluid flow control

ABSTRACT

A throttle body may have a main bore for supplying a fuel and air mixture to an engine. A throttle valve head may be received in the main bore and movable between idle and wide open positions to control fluid flow through the main bore. A main fuel outlet and a boost venturi may open to the main bore and a flow directing feature may alter the velocity and/or direction of fluid flow in the main bore relative to the fuel outlet or boost venturi. The flow directing feature may be carried by the body, the throttle valve head, or the boost venturi.

REFERENCE TO CO-PENDING APPLICATION

This application is a divisional of U.S. patent application Ser. No.16/331,394 filed Mar. 7, 2019, which is a national phase ofPCT/US2017/049837 filed Sep. 1, 2017 and claims the benefit of U.S.Provisional Application Ser. No. 62/385,673 filed on Sep. 9, 2016. Theentire contents of these priority applications are incorporated hereinby reference in their entireties.

TECHNICAL FIELD

The present disclosure relates generally to a throttle body forproviding a fuel and air mixture to an engine.

BACKGROUND

A variety of fuel injection throttle body configurations are known forsupplying a fuel and air mixture to an internal combustion engine tosupport its operation in which a liquid gasoline fuel is injected into amain bore at a relatively high pressure typically in the range of 6 to40 psi and sometimes up to 80 psi or more above ambient atmosphericpressure or 21 to 55 psi or more to facilitate mixing or dispersion ofthe liquid fuel in the fuel and air mixture supplied to the engine. Tocontrol the rate of flow of the mixture to the engine, a throttle valvewith a planar valve head in the main bore is carried on a shaft that isrotated to move the valve head between an idle position, associated withlow speed and/or low load engine operation, and a wide open or fullyopen position, associated with high speed and/or high load engineoperation. Typically a fuel pump and pressure regulator supplies liquidfuel at this high pressure to a fuel metering valve or injector which isopened and closed by an electronic controller such as a microcontrollerat defined times to discharge the appropriate quantity of fuel into themain bore for the current operating condition of the engine. Typicallythe fuel metering valve is located upstream of the throttle body valvehead or much further downstream of the throttle body and proximate tothe engine fuel intake port or engine intake valve pocket.

SUMMARY

In at least some implementations a throttle body may have a main borefrom which a fuel and air mixture is supplied to the engine, a throttlevalve head movable between an idle and a wide open position to controlat least some flow through the main bore to the engine, a main fueloutlet open to the main bore, and a flow directing feature altering atleast one of the velocity or direction of at least a portion of thefluid that flows in the main bore relative to the main fuel outlet. Inat least some implementations fuel flow through the main fuel outlet maybe electronically controlled. In at least some implementations the flowdirecting feature may direct a portion of air flowing in the main boretoward the main fuel outlet. In at least some implementations the mainfuel outlet discharges fuel into a boost venturi. In someimplementations the boost venturi may preferably be located downstreamof the throttle valve head. In some implementations, a main fuel outletdischarges fuel into the boost venturi and the flow directing featuredirects a portion of air flowing in the main bore into the boostventuri. In at least some implementations, the flow directing featuremay be carried by at least one of the throttle valve head, body and theboost venturi. In at least some implementations the flow directingfeature may include a non-planar portion of or carried by the throttlevalve head. In at least some implementations, one or more projectionsmay extend from the valve head. In at least some implementations, theflow directing feature may include a channel through which air flowingin the main bore is directed toward the boost venturi and in someimplementations the channel may be centered about a plane that includesa center axis of the boost venturi.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of preferred embodiments and bestmode will be set forth with reference to the accompanying drawings, inwhich:

FIG. 1 is a perspective view of a throttle body including a flowdirecting feature;

FIG. 2 is a sectional view of a throttle body showing a throttle valvewith at least one flow directing feature and a boost venturi;

FIG. 3 is an end view of the throttle valve of FIG. 2 ;

FIG. 4 is a perspective bottom view of a throttle valve head as shown inFIGS. 2 and 3 ;

FIG. 5 is a perspective view of a throttle body with portions showntransparent to illustrate a boost venturi and throttle valve with one ormore flow directors within the throttle body and a boost venturi;

FIG. 6 is a perspective view of a throttle body including a throttlevalve, boost venturi and a flow director separate from both the throttlevalve and boost venturi;

FIG. 7 is an end view of the throttle body of FIG. 6 ;

FIG. 8 is a fragmentary side view of a throttle body;

FIG. 9 is an end view of a throttle body showing a throttle valve andboost venturi;

FIG. 10 is a side view of a throttle valve with at least one flowdirecting feature;

FIG. 11 is an end view of the throttle valve of FIG. 10 ; and

FIG. 12 is partial perspective view of a throttle body including a boostventuri and a fluid outlet ports arranged in the boost venturi.

DETAILED DESCRIPTION

Referring in more detail to the drawings, FIGS. 1-3 illustrate athrottle body 10 that provides a fuel and air mixture to an engine tosupport operation of the engine. The throttle body 10 has a main body 12(typically cast metal) with a main bore 14 through which air flows froman inlet side 16, usually positioned adjacent to an air filter, to anoutlet side 18, usually positioned adjacent to an engine intake. Thethrottle body 10 also has one or more fuel circuits through which fuelis provided into the main bore 14 and combined with air flowing throughthe main bore 14 to form the fuel and air mixture. The fuel circuit(s)may include a fuel injector or other fuel metering device 20, throughwhich fuel is discharged into the main bore 14. In at least someimplementations, the fuel may be discharged at a pressure of 1 bar orless, including some systems having a fuel pressure of 0.35 bar or less.

The main bore 14 may have any desired shape including (but not limitedto) a constant diameter cylinder or a venturi shape wherein the inlet 16leads to a tapered converging portion that leads to a reduced diameterthroat that in turn leads to a tapered diverging portion that leads tothe outlet 18. The converging portion may increase the velocity of airflowing into the throat and create or increase a pressure drop in thearea of the throat. Especially when a fuel injector or other meteringdevice 20 is used and fuel is provided under some positive pressure, astraight cylindrical bore can be used as it provides less restriction toair flow compared to bores of non-uniform diameter or cross-sectionalarea, and the fuel flow provided through the control valve can bemetered to match the air flow over a wide range of conditions.

In at least some implementations, a secondary venturi, sometimes calleda boost venturi 21 may be located within the main bore 14 whether themain bore 14 has a venturi shape or not. The boost venturi 21 may haveany desired shape, and as shown in FIGS. 4 and 5 , has a converginginlet portion 22 that leads to a reduced diameter intermediate throat 24that leads to a diverging outlet 26. The boost venturi 21 may be coupledthe to throttle body 10 within the main bore 14, and in someimplementations, the throttle body may be cast from a suitable metal andthe boost venturi 21 may be formed as part of the throttle body, inother words, from the same piece of material cast as a feature of thethrottle body when the remainder of the throttle body is formed. Theboost venturi 21 may also be an insert coupled in any suitable manner tothe throttle body 10 after the throttle body is formed. In the exampleshown, the boost venturi 21 includes a wall 28 that defines an innerpassage 30 that is open at both its inlet 22 and outlet 26 to the mainbore 14. A portion of the air that flows through the throttle body 10flows into and through the boost venturi 21 which increases the velocityof that air and decreases the pressure thereof. The boost venturi 21 mayhave a center axis 36 that may be generally parallel to a center axis 38of the main bore 14 and radially offset therefrom, or the boost venturi21 may be oriented in any other suitable way. As shown in FIG. 2 , theboost venturi may be formed separately from the main body 12, as aninsert that is assembled into the main body after the main body isformed. In the example shown, the boost venturi 21 is supported at leastpartially by a cylindrical protrusion or a rod 40 (FIG. 3 ) that extendsfrom the main body 12, into the main bore 14 and to a boss or othersupport 42 in the wall 28 of the boost venturi. As also shown, the boostventuri 21 may be supported by a flange 44 extending from the wall 28and received within a slot or groove 46 in the main bore 14 (orconversely, a flange extending from the body 12 in the main bore 14 andreceived within a slot in the wall 28). The support and flange 42, 44may be generally diametrically opposed and arranged so that the boostventuri 21 is supported at a desired height within the main bore 14which may, but need not, locate a bottom surface of the wall 28 againsta surface of the main body 12 that defines the main bore 14.

The throttle body 10 may include a throttle valve 48 carried by the mainbody 12 for adjusting the flow rate of the fuel and air mixture out ofthe throttle body 10. The throttle valve 48 includes a throttle shaft 50and a throttle valve head 52 mounted, such as by one or more screws 54,to the throttle shaft 50. The throttle shaft 50 is rotatably carried byor relative to the body 12 and extends transversely across the main bore14 to enable rotation of the throttle valve head 52 relative to the mainbore. In at least some implementations, the throttle valve head 52 isdefined by a flat disc commonly referred to as a butterfly valve head.The throttle valve 48 is rotated between an idle position and a wideopen position, and may be operated at various positions in between thosetwo positions. In the idle position, the throttle valve head 52 issubstantially transverse to the axis 38 of the main bore 14, and may berotated between about 3 and 20 degrees from a plane that is transverseto the axis 38. In this position, the throttle valve head 52 provides amaximum restriction to air flow out of the main bore 14, but allowssufficient air or fluid flow to support idle engine operation. In thewide open position of the throttle valve 48, shown in FIG. 2 , thethrottle valve head 52 typically is generally parallel to the axis 38 ofthe main bore 14 (where generally parallel is within 10 degrees ofparallel), and provides a minimum restriction to air flow out of themain bore and to the engine. The throttle valve head 52 is disposedadjacent to the inlet side 16 of the throttle body, and upstream of (atleast when the throttle valve is in its idle position) a main fueloutlet 56 and the boost venturi 21.

The main fuel outlet 56 opens into or is otherwise communicated with themain bore 14 and is in communication with the fuel metering device 20(e.g. a fuel injector or a fuel flow control valve) to enable fuel flowinto the main bore 14. The fuel metering device may be carried by thebody 12 and may provide a metered flow of fuel into a fuel passageleading to the fuel outlet 56. The main fuel outlet 56 may include aport which may be formed in the body 12 or defined by an insertassembled into the body, such as the rod 40 coupled to the boost venturi21 which may be hollow and define a fuel passage. The main fuel outlet56 may be located between the inlet and outlet sides 16, 18 of the mainbore 14 and may be within or downstream of a narrower portion of themain bore (if provided) which acts as a venturi to increase flowvelocity and decrease fluid pressure near the main fuel outlet 56. Ofcourse, the main bore need not have a venturi portion or venturi shape,as noted above. In at least some implementations, the fuel outlet 56 anda center of the boost venturi (taken perpendicular to the boost venturiaxis 36) may be located closer to the outlet 18 of the main bore thanthe inlet 16. The fuel outlet 56 may be a simple port open to the boostventuri passage 30, may be defined in a conduit or tube 40 extendinginto the boost venturi 21, and/or may include more than one opening orport open into the boost venturi or downstream thereof.

In one example shown in FIG. 12 , the fuel outlet includes more than oneport 58 formed in a tube 59 that extends across the boost venturi 21perpendicular to the direction of fluid flow through the boost venturi,and the ports may face downstream (i.e. toward the outlet end 18). Thetube 59 may create boundary layer flow effect as the air flows aroundthe tube and that may improve mixing of the fuel and air. The tube 59also reduces the air flow area in that location of the boost venturi 21which may increase air flow velocity. The downstream facing ports 58 mayalso reduce the effects that transient reverse flow pressure waves haveon the fuel ports, to reduce or eliminate multiple fuel discharge eventsdue to such transient waves.

To aid in directing air flow in the area of the main fuel outlet 56, aflow directing feature may be associated with, such as by being carriedby, at least a portion of the throttle valve head 52. In the embodimentof FIGS. 1 and 2 , one flow directing feature is implemented by a bent,curved or otherwise non planar portion 60 of the throttle valve head 52.The non-planar portion 60 of the throttle valve head 52 is provided in adownstream portion of the throttle valve head and it is oriented so thatit is angled toward the boost venturi and/or the main fuel outlet whenthe throttle valve 48 is in its second or wide open position. Thenon-planar portion 60 may be provided at an angle of between 1 and 170degrees relative to the remainder of the throttle valve head 52. Wherean angle of 80 degrees is perpendicular to air flow, angles of 80degrees or more may tend to cause turbulence and may be useful whereincreased mixing of fluid is desired (although such angles may be usedfor other reasons). Angles less than 80 degrees, and particularly lessthan 45 degrees, for example between 3 and 45 degrees, may more smoothlyguide or direct fluid flow, in at least some implementations. Thenon-planar portion 60 may begin downstream of the throttle valve shaft,if desired. Of course, the bent or angled non-planar portion 60 could beprovided in any suitable location or orientation to direct/control airflow as desired, including at a different angle relative to the airflowand starting/ending at different locations along the throttle valve head52. Further, more than one area may be angled or offset relative toother portions of the throttle valve head 52, and/or more than one bendmay be provided.

Also, as shown in FIG. 1 , when the throttle valve 48 is in its secondposition, the throttle valve head 52 substantially divides into twosections the portion of the main bore 14 in which the throttle valvehead is received. A first section 61 is directly open to the main fueloutlet 56 and adjacent to a first side 64 of the throttle valve head 52,and a second section 63 is spaced and generally separate from the mainfuel outlet 56 and adjacent to an opposite, second side 66 of the head52. Thus, air flowing into the main bore inlet 16 when the throttlevalve is in its open position is divided into two streams by thethrottle valve head 52, at least temporarily or during at least aportion of the length of the main bore between the inlet 16 and theoutlet 18. The streams may converge and join together downstream of thethrottle valve head 52 and a single output fluid flow may be providedfrom the outlet end 18 of the main bore 14.

In addition to increasing fluid flow velocity near the main fuel outlet56, the non-planar portion 60 of the throttle valve head 52 can alsodirect the air flow in the first section 61 away from the second section63 to maintain and even promote separation of the fluid streams. In thisregard, the non-planar portion 60 of the throttle valve head 52 mayextend to or within 3 mm of the downstream edge 68 of the throttle valvehead 52, and may serve to provide a more consistent stream of air to theinlet of the boost venturi 21 to enable some control over the fluid flowin and through the boost venturi over a wider range of throttle valvepositions and engine operating conditions.

In addition to or instead of the non-planar portion 60 of the throttlevalve head 52, a second flow directing feature 70 may be provided in thearea of the boost venturi 21. This flow directing feature 70 may beseparate from the throttle body main body 12 (e.g. not a restrictionformed in the main bore 14) and is arranged to direct and control airflow in the area of the boost venturi or main fuel outlet if no boostventuri is provided. In the implementation shown in FIGS. 1-3 , the flowdirecting feature 70 includes one or more projections 72 carried by thethrottle valve head 52 and defining a further non-planar portion of thethrottle valve head 52. The projections 72 may be formed integrally inthe same piece of material that defines the remainder of the throttlevalve head 52 including the first flow directing feature (e.g.non-planar portion 60), or they may be separate components that are eachattached to or otherwise carried by the throttle valve head 52, or theymay be connected together within a separate component that is attachedto the throttle valve head 52. As shown, the projections 72 extendoutwardly from the first side 64 of the throttle valve head 52 anddefine a channel 74 between them. In this implementation, theprojections 72 are cantilevered on the valve head 52 such that eachprojection 72 has a free end 76 and the channel 74 is not enclosed. Ifdesired, the projections could be joined together (e.g. at the freeends) by a spanning wall to define an enclosed channel of any desiredshape. Further, while the projections 72 are shown as generally straightor planar, they could be curved or bent in any desired shape and of anydesired size, spacing and orientation. FIGS. 10 and 11 illustrateanother example of throttle valve head 52′ with projections 72′ and anon-planar portion 60′ defining a further flow directing feature this isformed by a groove or other void, instead of an outward projection as inthe first example non-planar portion 60. Still other arrangements offlow directing features may be used.

As shown in FIGS. 3 and 4 , the channel 74 includes an inlet end 78upstream of an outlet end 80, and the inlet and outlet ends aregenerally aligned with regard to the direction of fluid flow in the mainbore 14. The distance between the projections 72 is less at the outletend 80 than the inlet end 78 (i.e. the projections converge toward theoutlet end) so the channel narrows from the inlet end 78 to the outletend 80. Because of this, air flowing through the channel 74 tends toincrease in velocity from the inlet end 78 to the outlet end 80, and airis further directed by the channel 74 toward the main fuel outlet 56.Thus, in this example, both the non-planar portion 60 of the throttlevalve head 52 and the projections 72 tend to increase the velocity of atleast some of the fluid in the first section 61 of the main bore 14, anddirect some of that fluid stream toward the boost venturi 21.

When used with a throttle valve head 52 having a non-planar portion 60,at least part of the projections 72 may extend along at least a portionof the non-planar portion 60 of the throttle valve head 52. Thus, bothflow directing features 60, 70 work together in promoting a desired airflow through at least part of the main bore 14. As best shown in FIGS. 1and 2 , the projections 72 may extend away from the first side 64 of thethrottle valve head 52 and may radially overlap at least a portion ofthe boost venturi 21 when the throttle valve 48 is in its second orfully open position. A downstream end of the projections may axiallyoverlap at least part of the boost venturi (e.g. the inlet end), ifdesired, or be within about 1 mm of the inlet end of the boost venturifor clearance purposes or otherwise. Hence, the increased velocity airstream through the channel 74 is directed close to and toward the boostventuri 21 and may have its maximum velocity at or near the center ofthe boost venturi 21 to provide a greater pressure drop across the boostventuri. Still further, the trailing or downstream edge of the throttlevalve head 52 may be located between 2 mm and 8 mm from the inlet 22 ofthe boost venturi. If the throttle plate is too far away, the air flowfrom the flow directing features will dissipate and the effects thereofwill be reduced. If the throttle plate is too close, the airflow mightbe turbulent and not as predictable, and/or the movement of the throttleplate may be interfered with by the boost venturi.

In FIG. 5 , the projections 82 are defined or carried by fasteners 84that connect the throttle valve head to the valve shaft. The fasteners84 or other projections 82 extend outwardly from the valve head 52 andare arranged to extend into the second section 63 of the main bore 14when the throttle valve 48 is in its second position. The projections 82disrupt the air flow and produce three separate streams—one between thesurface of the main bore 14 and a first projection, a second between thesurface of the main bore and second projection and a third in a channel86 defined between the projections 82. The streams are only temporarilyseparate and then join together downstream of the projections 82 andupstream of the boost venturi 21. In at least some implementations, thethird stream that flows between the projections 82 may be aligned withthe boost venturi inlet 22 and serve to provide a more direct air flowsource to the boost venturi 21 for more consistent fluid flow in andthrough the boost venturi. The projections 82 may have a length, sizeand shape as desired to create desired air streams, eddies and otherflow qualities to provide a desired flow rate and/or pressure signal ator across the boost venturi 21. In the example shown, the projections 82are generally right cylindrical bodies that extend perpendicular to theface of the throttle valve head 52, although other shapes andorientations may be used.

While shown as extending within the first section 61 of the main bore 14(i.e. a section including or aligned in the direction of air flow withthe boost venturi 21), a flow directing feature may be used elsewhere inthe throttle body 10. For example, the second side 66 of the throttlevalve head 52 could include a flow directing feature arranged to directflow out of the second section of the main bore and toward the boostventuri or otherwise as desired. As just one other example, fluid in thesecond section 63 could be directed away from the first section 61 to,for example, encourage mixing of an air stream with a fuel and airmixture downstream of the boost venturi. Further, while the offset orangled non-planar portion 60 of the throttle valve head 52 may bedefined by a bend in the throttle valve head 52, it could be implementedin a thicker portion of the throttle valve head. The second side 66 ofthe throttle valve head 52 could be planar (e.g. not include a bend) oreven include an angled or ramped surface directed away from the firstsection 61 of the main bore 14. The throttle valve head 52 may be formedfrom any suitable material, such as various metals and plastics, withall features formed in one, integral piece of material, or from multiplepieces of material.

Further, as shown in FIGS. 6 and 7 , a flow directing feature 90 may beprovided in the main bore 14 and within the second section 63 torestrict air flow in the second section and encourage air in the secondsection to flow toward the first section 61. The flow directing feature90 may be carried by the main body 12 so that it projects at leastpartially into the main bore 14. In the example shown, the flowdirecting feature includes a projection 90 extending across the mainbore 14, is not parallel to the axis 38 of the main bore, and is in theform of a cylindrical rod 90 that in at least some implementations maybe arranged parallel to the throttle valve shaft 50 and is connected tothe main body at both ends. Of course, the projection 90 may have othershapes and orientations, and more than one projection may be provided.The rod 90 divides air flowing in the second section 63 into twostreams, one stream above and one stream below the rod, with the streamflowing below the rod directed toward the first section 61 and the boostventuri 21 therein. This may assist or increase air flow into the boostventuri inlet 22 and/or encourage or improve mixing of air in the mainbore 14 with the air and fuel mixture discharged from the boost venturi.

One or more flow directing features may also be formed on, carried by orassociated with the boost venturi 21. In the examples shown in FIGS. 8and 9 , the boost venturi includes a projection 100, 100′ that extendsupstream of the boost venturi inlet 22 and is arranged to direct airinto the inlet. In the example shown in FIG. 8 , the projection 100includes an inclined ramp surface 102 arranged to direct air flowingadjacent to the surface of the main bore 14 to the inlet 22 which may bespaced from the surface of the main bore 14. As shown in FIG. 9 , theprojection 100′ includes a surface 102′ that is inclined and also curvedin a direction perpendicular to the air flow in the main bore 14 toprovide at least partially raised sides, and a projection that is aportion of a cylinder or generally scoop-shaped to direct more air tothe inlet 22. While shown as extending along a lower surface of the mainbore 14 and to a lower portion of the inlet 22, a projection couldinstead or also be positioned adjacent to an upper portion of the boostventuri, and/or a side of the boost venturi to direct air toward theinlet as desired. In at least some implementations, the projection maydefine a complete or partial funnel or other structure that is larger atits upstream end spaced from the inlet than at its downstream endadjacent to the inlet.

Further, the throttle valve head 52 may include an opening 104 throughwhich air flows when the throttle valve is in its first position (e.g.idle) and in positions between the first and second positions (e.g. upto 50% of throttle valve movement away from the idle position), as shownin FIG. 9 . The opening may be oriented or positioned as desired, andmay be generally aligned with the boost venturi 21 when the throttlevalve 48 is in its first position to direct air flow to or toward theboost venturi and provide a desired air flow rate and/or pressure signalat the boost venturi. Among other things, this may promote flow out ofthe boost venturi 21, and mixing of the fuel and air. The opening 104may also be considered a flow directing feature and may advantageouslypromote a desired fluid flow in the main bore 14. The opening 104 may bedefined by a simple hole through the valve head 52, a notch of flat onan edge of the valve head or in a lengthier projection extending fromand carried by the valve head.

A throttle valve head 52 may be mounted off-center relative to the mainbore 14 such that one of the two sections 61, 63 is larger than theother, as desired. In other words, a rotational axis 106 of the throttlevalve shaft 50 does not intersect the axis 38 of the main bore 14. In atleast some implementations, the main bore axis 38 may extend between thethrottle valve shaft axis 106 and the boost venturi axis 36. Hence, whenthe throttle valve 48 is in its second or open position, more than halfof the area of the main bore 14 may be open in the first section 61, andthe flow directing features may then direct more air toward the fueloutlet and/or boost venturi. In at least some implementations, thethrottle shaft axis 106 may be offset from the main bore axis 38 bybetween 0.5 mm to 6 mm (and as noted above this may make the firstsection 61 larger than the second section 63) for main bores having adiameter between 18 mm and 40 mm.

Further, a throttle valve head 52 may be provided with any one of, orany combination of, the various flow directing features described hereinas well as modified flow directing features that persons of ordinaryskill in the art will readily devise in view of the teachings herein. Inother words, these features may be used separately or in any desiredcombination. Further, while various features were described thatincrease fluid flow velocity, flow directing features could also beprovided that decrease a fluid flow velocity. Likewise, while certainfeatures were described as promoting separation of two fluid flows, flowdirecting features like those disclosed herein could also be implementedto encourage mixing of fluid within the throttle body. Still further,the features discussed herein, separately or in any combination, couldalso be implemented on or associated with the throttle valve.

While representative flow directing features have been shown in thesefigures, many more shapes, sizes and orientations are possible; theillustrated implementations are not intended to limit the scope of thedisclosure in any way. Further, the valve heads shown herein can beoriented in different ways/directions relative to the direction of airflow and need not be in the orientations shown in the drawings.

The flow directing features and boost venturi downstream of the throttlevalve may, among other things, provide improved mixing of fuel and airin the main bore. Additionally, the throttle body so arranged mayprovide an improved pressure signal at the fuel outlet to improve engineoperation during low speed and high load operating conditions that cancause engine lugging, provide a low cost system that provides fuel atrelatively low pressure compared to higher pressure fuel injectedsystems, provide striation of air flows between the first and secondsections of the main bore with the ability to provide more airflow inthe first section and to the boost venturi if desired, control airflowand pressure signals at the fuel outlet to enhance management of thefuel and air mixture provided from the throttle body.

While the forms of the invention herein disclosed constitute presentlypreferred embodiments, many others are possible. For example, the flowdirecting features can have other shapes, orientations, locations andfunctions as would be appreciated by persons of ordinary skill in thisart in view of this disclosure. It is not intended herein to mention allthe possible equivalent forms or ramifications of the invention. It isunderstood that the terms used herein are merely descriptive, ratherthan limiting, and that various changes may be made without departingfrom the spirit or scope of the invention.

The invention claimed is:
 1. A throttle body, comprising: a body havinga main bore from which a fuel and air mixture is discharged for use byan engine, the main bore having an inlet side into which air flows intothe main bore and an outlet side from which air and fuel exit the mainbore; a throttle valve head carried by the body and moveable between anidle position and an open position to control at least some fluid flowthrough the main bore; a boost venturi open to the main bore andarranged between the throttle valve head and the outlet side of the mainbore; and a flow directing feature to alter at least one of the velocityor direction of at least a portion of the fluid that flows in the mainbore and relative to the boost venturi, the flow directing feature beingcarried by the body separate from the throttle valve head and the boostventuri, and wherein the flow directing feature is arranged downstreamof the throttle valve head and upstream of an inlet of the boostventuri, where downstream and upstream are with regard to a direction offluid flow through the main bore.
 2. The throttle body of claim 1wherein the flow directing feature projects at least partially into themain bore.
 3. The throttle body of claim 1 wherein the flow directingfeature is radially offset from the boost venturi relative to a centeraxis of the main bore.
 4. The throttle body of claim 3 wherein thecenter axis extends between the flow directing feature and the boostventuri.
 5. The throttle body of claim 2 wherein the flow directingfeature is arranged so that fluid may flow around two opposite sides ofthe flow directing feature.
 6. The throttle body of claim 1 wherein thethrottle valve head includes an opening formed through the throttlevalve head, wherein the opening is oriented to direct an air flow at theboost venturi when the throttle valve head is in the idle position. 7.The throttle body of claim 1 which also includes a second flow directingfeature carried by the boost venturi upstream of the inlet of the boostventuri.
 8. The throttle body of claim 7 wherein the boost venturi hasthe inlet in which air is received and an outlet from which air exitsthe boost venturi, and the second flow directing feature includes aninclined surface arranged to direct air into the boost venturi.
 9. Athrottle body, comprising: a body having a main bore from which a fueland air mixture is discharged for use by an engine, the main bore havingan inlet side into which air flows into the main bore and an outlet sidefrom which air and fuel exit the main bore; a throttle valve headcarried by the body and moveable between an idle position and an openposition to control at least some fluid flow through the main bore; aboost venturi open to the main bore and arranged between the throttlevalve head and the outlet side of the main bore; and a flow directingfeature to alter at least one of the velocity or direction of at least aportion of the fluid that flows in the main bore and relative to theboost venturi, the flow directing feature being carried by the bodyseparate from the throttle valve head and the boost venturi, wherein theflow directing feature extends fully across the main bore.
 10. Thethrottle body of claim 9 wherein the flow directing feature is spacedfrom a central axis of the main bore.
 11. The throttle body of claim 9wherein the throttle valve head having a first side and a second sideopposite to the first side, the main bore having a first section definedin part by the first side of the throttle valve head when the throttlevalve head is in the open position, and the main bore has a secondsection defined in part by the second side of the throttle valve headwhen the throttle valve head is in the open position, and wherein theflow directing feature is located within the first section and the boostventuri is located within the second section.
 12. The throttle body ofclaim 9 wherein the flow directing feature is a cylindrical rod spacedfrom the throttle valve head.
 13. A throttle body, comprising: a bodyhaving a main bore from which a fuel and air mixture is discharged foruse by an engine, the main bore having an inlet side into which airflows into the main bore and an outlet side from which air and fuel exitthe main bore; a throttle valve head carried by the body and moveablebetween an idle position and an open position to control at least somefluid flow through the main bore; a boost venturi open to the main boreand arranged between the throttle valve head and the outlet side of themain bore; a flow directing feature to alter at least one of thevelocity or direction of at least a portion of the fluid that flows inthe main bore and relative to the boost venturi, the flow directingfeature being carried by the body separate from the throttle valve headand the boost venturi; and a tube extending from the main body to theboost venturi and defining a fuel passage having a fuel outlet withinthe boost venturi.
 14. The throttle body of claim 13 wherein the tubeextends into an inner passage of the boost venturi, with at least oneport formed in the tube, with fuel flowing through the port and into theinner passage.
 15. The throttle body of claim 14 wherein the at leastone port faces away from an inlet of the boost venturi and toward anoutlet of the boost venturi.
 16. The throttle body of claim 15, whereinthe at least one port includes multiple ports each oriented in the samedirection.